Mapping of HSs in homozygous ▵5,6 ▵H/▵5,6 ▵H mice. A DNase I series of erythroid tissue from a homozygous mutant mouse was digested with Hpa I (H) and hybridized with a 5′ probe (the same enzyme and probe combination as used in Fig4). Although 5′ HS 4, 4.1, and 4.2 form, no HS forms at the site of the deletion. Molecular size standards are marked on the left. The size of the parent band, placement of the probe used, and the size of the degradation bands are diagrammed below.